Non-viral gene transfer procedures are needed for human gene therapy in order to achieve long-term maintenance and expression of newly introduced genes. The purpose of this project is to evaluate the efficacy of the Sleeping Beauty transposon system as a gene transfer vector for gene therapy. The transposon system is binary, consisting of a transposon containing a transgene and a source of transposase enzyme. The transposase is able to mediated enhanced integration of marker/reporter genes in several mammalian culture cell lines in vitro as well as in fertilized vertebrate. Here, the examination of transposon system will be extended to liver cells, ranging from tissue-cultured hepatoma cells, to primary hepatocytes and livers of whole animals. Liposomes complexed with lactosylated DNA condensing agents will be used to deliver the transposon system. Genes that are involved human genetic disease, and for which the transposon system. The successful demonstration of transposition of new sequences into mammalian cells would constitute a proof-of-principle for using this integrating mechanism in humans for gene therapy that does not employ viral vectors.